[AIRFLOW-3007] Update backfill example in Scheduler docs

[kaxil]

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Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-3007
  • In case you are fixing a typo in the documentation you can prepend your commit with [AIRFLOW-XXX], code changes always need a Jira issue.

Description

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  The scheduler docs at https://airflow.apache.org/scheduler.html#backfill-and-catchup use deprecated way of passing schedule_interval. schedule_interval should be pass to DAG as a separate parameter and not as a default arg.

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Documentation

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Code Quality

• Passes git diff upstream/master -u -- "*.py" | flake8 --diff

[r39132]

Good catch! +1